Patches were submitted to mailing review:
https://lists.ubuntu.com/archives/kernel-team/2020-August/112961.html
** Also affects: linux-azure-4.15 (Ubuntu)
Importance: Undecided
Status: New
** Also affects: linux-azure (Ubuntu Focal)
Importance: Undecided
Status: New
** Also affects: linux-azure-4.15 (Ubuntu Focal)
Importance: Undecided
Status: New
** Also affects: linux-azure (Ubuntu Bionic)
Importance: Undecided
Status: New
** Also affects: linux-azure-4.15 (Ubuntu Bionic)
Importance: Undecided
Status: New
** Changed in: linux-azure (Ubuntu Bionic)
Status: New => Invalid
** Changed in: linux-azure-4.15 (Ubuntu Focal)
Status: New => Invalid
** Changed in: linux-azure (Ubuntu Focal)
Status: New => In Progress
** Changed in: linux-azure-4.15 (Ubuntu Bionic)
Status: New => In Progress
** Changed in: linux-azure (Ubuntu)
Assignee: (unassigned) => Marcelo Cerri (mhcerri)
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You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux-azure in Ubuntu.
https://bugs.launchpad.net/bugs/1874503
Title:
Mellanox Check For Write Combining Support
Status in linux-azure package in Ubuntu:
New
Status in linux-azure-4.15 package in Ubuntu:
New
Status in linux-azure source package in Bionic:
Invalid
Status in linux-azure-4.15 source package in Bionic:
In Progress
Status in linux-azure source package in Focal:
In Progress
Status in linux-azure-4.15 source package in Focal:
Invalid
Bug description:
[Impact]
Microsoft and Mellanox would like to request the following two commits
in the releases that run on Azure:
3f89b01f4bba IB/mlx5: Align usage of QP1 create flags with rest of mlx5
defines
11f552e21755 IB/mlx5: Test write combining support
These commits landed in mainline as of v5.5-rc1.
These commits will improved network performance of RDMA out of the VF
when WC can be used. The highest benefit is to RDMA and DPDK, but UCX
should also see improved latency.
The Mellanox driver uses WC to optimize posting work to the HCA, and
getting this wrong in either direction can cause a significant
performance loss. These patches prevent the possible performance
loss.
[Test Case]
Simply measure the network performance with the patches applied to
check if there was some gain.
[Regression Potential]
It affects mainly the mlx5 driver and IB, while many of the instances
do not make use of those, they are used by the high performance users.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux-azure/+bug/1874503/+subscriptions
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